There are two kinds of studio monitors concerning the powering: passive, and active. The most common one are the active studio monitors which have an one or more amplifiers build in and an active crossover. Now let’s talk about the 2 ways active studio monitors. They can be single amplified, which means that they have a single amplifier build in for the low and high frequencies, and double amplified, which means that they have separate amplifiers, one for low and one for high frequencies. The best biamp is the class D. Another thing which you should consider when you chose an active monitor are the built-in controls like trim, room, gain.